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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Transactions of the Korean Institute of Power Electronics
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Journal DOI :
The Korean Institute of Power Electronics
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Volume & Issues
Volume 8, Issue 6 - Dec 2003
Volume 8, Issue 5 - Oct 2003
Volume 8, Issue 4 - Aug 2003
Volume 8, Issue 3 - Jun 2003
Volume 8, Issue 2 - Apr 2003
Volume 8, Issue 1 - Feb 2003
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A Novel 11-Level PWM Inverter for Improving Output Voltage Waveform
The Transactions of the Korean Institute of Power Electronics, volume 8, issue 2, 2003, Pages 99~106
This paper presents a novel multilevel PWM inverter employing series-connected transformers in order to improve the waveshape of output voltage and to reduce its harmonics. The proposed 11-level inverter consists of three full-bridge inverter modules and their corresponding transformers. Among their inverter modules, one is used as PWM operation and the others as level generation. From a suitable selection of turns ratio of transformer, continuous output voltage levels were generated appearing an integral ratio to input DC source. Because of their series connection of transformers, output filter inductor is not necessary. The operational principles and analysis are explained, and it is compared with a conventional multilevel PWM inverter. The validity of the proposed system Is verified through the experimental results using a prototype.
The Sensorless Control of PMSM Using the Coordinate Transform and Differential Method
The Transactions of the Korean Institute of Power Electronics, volume 8, issue 2, 2003, Pages 107~115
PMSM(permanent magnet synchronous motor) are widely used in industrial and home appliance because of their high torque to inertia ratio, superior power density, and high efficiency For the high control performance, accurate information of rotor position Is essential. In recent, sensorless algorithms are much studied due to high cost problem of position sensor and low reliability in harsh environment. In the proposed method, a differential linkage flux is used for the estimation of rotor position. The differential magnetic field flux is calculated by the voltage equations and measured phase current without any integration and differential calculus. Instead of linkage flux calculation with differential operation, a new mathematical differential method is introduced by a-
transformation. The proposed novel position sensorless speed control scheme is verified through experimental results.
Design of Robust Double Digital Controller to Improve Performance for UPS Inverter
The Transactions of the Korean Institute of Power Electronics, volume 8, issue 2, 2003, Pages 116~127
In this paper, a new fully digital control method for UPS inverter, which is based on the double control loop such as the outer voltage control loop and inner current control loop, is proposed. In the proposed control system, overshoots and oscillations due to the computation time-delay are compensated by explicit incorporation of the time-delay in the current control loop transfer function. The inner current control loop is adopted by an Internal model controller The Internal model controller is designed to a second order deadbeat reference-to-output response which means that its response reaches the reference in two sampling time including computational time-delays. The outer voltage control loop employing P-Resonance controller is proposed. The resonance controller has an infinite gain at resonant frequency, and the resonant frequency is set to the fundamental frequency of the reference voltage in this paper. Thus the outer voltage control loop causes no steady state error as regard to both magnitude and phase. The effectiveness of the proposed control system has been verified by the simulation and experimental results respectively.
Anti-Windup Scheme to Control DC Voltage of Three-Phase Four-Wire Active Power Filter
The Transactions of the Korean Institute of Power Electronics, volume 8, issue 2, 2003, Pages 128~136
This paper investigates the application of the anti-windup scheme to control U voltage of the three-phase four-wire active power filter, installed in a three-phase four-wire power system. In order to reduce efficiently the harmonic currents caused by the switching loads and to improve the whole performance of the flower system, the DC voltage of the three-phase four-wire active power filter should be properly controlled. PI controller can be applied to the U voltage controller of the three-phase four-wire active power filter. However, a large error input to PI controller leads to a windup phenomenon which deteriorate the dynamic characteristics of the U voltage controller Therefore, the application of the anti-windup scheme for the DC voltage controller is proposed and the improved performances of the anti-windup U voltage controller are proved through the computer simulation study.
Alternative Derivation of Continuous-Time Model for Current-Mode Control
The Transactions of the Korean Institute of Power Electronics, volume 8, issue 2, 2003, Pages 137~142
Two existing continuous-time models for the current-mode control have presented noticeable differences in their small-signal predictions. As an attempt to clarify the origin of these disparities, this paper presents an alternative way of deriving a continuous-time model for the current-model control. The results of this paper would provide insights to comprehend the dissimilarity in the modeling method and final results of the earlier models of current-mode control models.
An Improved MPPT Converter with Current Compensation Method for Small Scaled PV-Applications
The Transactions of the Korean Institute of Power Electronics, volume 8, issue 2, 2003, Pages 143~150
An improved MPPT converter with current compensation method for small-scaled PV-applications is presented in this paper. The proposed method implements maximum power point tracking (MPPT) by variable reference current which is continuously changed during one sampling period. Therefore, the Power transferred to the load is increased above 9% by the proposed MPPT converter with current compensation method. As a result, the utilization efficiency of Photovoltaic (PV)-panel can be increased. In addition, as it doesn't use digital signal processor (DSP), this MPPT method has the merits of both a cost efficiency and a simple control circuit design. Therefore, it is considered that the proposed MPPT method is proper to low power, low cost PV-applications. The concept and control principles of the proposed Un moth()d are explained in detail and its validity of the proposed method is verified through several simulated results.
Induction Motor Drives with Low Switching Acoustic Noise Based on the Two-Phase Modulated Random Lead-Lag PWM Scheme
The Transactions of the Korean Institute of Power Electronics, volume 8, issue 2, 2003, Pages 151~164
In this paper, induction motor drives with low switching acoustic noise based on the 2 phase modulated RLL(Random Lead-Lag) PWM is proposed and implemented. The proposed switching method is much bettor than 3 phase modulated RLL-PWM from the standpoint of the broadening effect of the acoustic noise spectrum. Along with the randomization of PWM Pulses, SVM(Space Vector Modulation) is executed in the TMS320C31 DSP(Digital Signal Processor). To verify the validity of the proposed RPWM(Random PWM), the experimental study was tried. The experimental results show that the performance of the proposed method and the 3 phase center-aligned SVM / conventional RLL-PWM are nearly the same from the viewpoint of the constant v/f centrel. But, in case of the proposed 2 phase modulated RLL-PWM, the spectrum characteristics of the voltage and the switching acoustic noise are shown to have better broadening effect than 3 phase modulated one.
Design of Current Controller for an Induction Motor using Robust Stability Theory
The Transactions of the Korean Institute of Power Electronics, volume 8, issue 2, 2003, Pages 165~172
In this paper, the new robust current control scheme is proposed for an Induction motor. The proposed design scheme of current controller tan obtain a specified stability margin through electrical parameter variation by using Kharitonov robust stability theory. The characteristics of the proposed design scheme are compared with those of a conventional scheme by computer simulation and its effectiveness and usefulness is verified by experiments on the 0.75kW induction motor drive.
Capacitance Estimation of DC-Link Capacitors of Three-Phase AC/DC/AC PWM Converters using Input Current Injection
The Transactions of the Korean Institute of Power Electronics, volume 8, issue 2, 2003, Pages 173~179
In this paper, a novel on-line dc capacitance estimation method for the three-phase PWM converter is proposed. At no load, input current at a low frequency is injected, which causes dc voltage ripple. With the at voltage and current ripple components of the dc side, the capacitance can be calculated. Experimental result shows that the estimation error is less than 2%.
A Study on the PSPICE Modeling of CCFL Drive Circuit Using a Piezoelectric Transformer
The Transactions of the Korean Institute of Power Electronics, volume 8, issue 2, 2003, Pages 180~191
In this paper, the modelings of PSPICE of the piezoelectric transformer and CCFL drive circuit using an electrical equivalent circuit is proposed. In the CCFL drive circuit modeling the model parameters of the CCFL were derived using the method of least squares because push-pull inverter and loads such as CCFL were also modeled using PSPICE. It is considered that the simulation techniques can be used in the piezoelectric devices such as piezoelectric transformer.
High Frequency High Voltage 40kW Power System for Diagnosis X-ray
The Transactions of the Korean Institute of Power Electronics, volume 8, issue 2, 2003, Pages 192~198
Recently, the Inverter type X-ray generator is rapidly replacing the conventional single-phase or three-phase X-ray generator, it has several merits of space-saving: high accuracy and reproducibility. This paper presents a 40kw(12kV, 80mA) high tension generator system for diagnosis X-ray. The control circuit and design consideration of the proposed high tension power supply are given. Issues in the design of high voltage isolating transformer are discussed. Experimental results are presented to verify the performance of the designed power supply for varying load conditions. 1'he proposed apparatus has several advantages, e. g., the fast rising time of tube voltage, accuracy and reduced component size etc.
Islanding Detection by Harmonic Current Injection Method for Utility Interactive Photovoltaic System
The Transactions of the Korean Institute of Power Electronics, volume 8, issue 2, 2003, Pages 199~210
In this paper, the new Islanding detection method is studied for utility interactive photovoltaic system(UIPVS). It describes the brief of UIPV system and the features of islanding phenomenon. The new islanding detection method for improving the detection characteristics, HCIM(Harmonic Current Injection Method), is proposed and analyzed. The impedance curve of AC load is derived from the complex power equation for testing Islanding detection features. The proposed detection method and the derivation of islanding condition we verified by the simulation with ACSL and the laboratorial experiments.